高应力水平区混凝土试件蠕变特性及失稳机制  

Creep characteristics and instability mechanism of concrete specimen in high-stress area

作　　者：辛亚军[1,2] 安定超 郝海春 XIN Yajun1＇2, AN Dingchao1, HAO Haichun1(1. School of Energy Science and Engineering, Henan Polytechnic University, Jiaozuo, Henan 454000, China; 2. The Collaborative Innovation Center of Coal Safety Production of Henan Province, Jiaozuo, Henan 454000, Chin)

机构地区：[1]河南理工大学能源科学与工程学院,河南焦作454000 [2]煤炭安全生产河南省协同创新中心,河南焦作454000

出　　处：《采矿与安全工程学报》2018年第2期382-390,共9页Journal of Mining & Safety Engineering

基　　金：国家自然科学基金项目(51174078);河南省教育厅科学技术研究重点项目(14B440001);河南省焦作市科技攻关计划项目(20151021103453);河南理工大学博士基金项目(B2014-054)

摘　　要：高应力水平区混凝土试件蠕变特性复杂,在实验室通过RLW-2000型三轴伺服流变仪,对2组20个相同规格混凝土试件进行了2种加载速率条件下的单轴抗压强度和单轴压缩蠕变试验,研究了混凝土试件蠕变应变速率与应力水平的关系,分析了混凝土试件高应力水平区的蠕变特性及强度特征,确定了混凝土试件蠕变破坏形态及失稳机制,建立了混凝土试件高应力水平区蠕变模型,对比了蠕变试验曲线与理论曲线的关系。结果表明:在高应力水平区经历的应力水平级数越少,试件蠕变破坏的蠕变应变速率越大,随着蠕变破坏应力水平增加,蠕变应变速率整体呈减小趋势;高应力水平区混凝土试件蠕变破坏总应变大于瞬时破坏总应变,蠕变破坏强度是瞬时强度的79.97%~88.85%;高应力水平区混凝土试件蠕变破坏主要表现为压缩劈裂破坏,试件局部出现"X"形压剪破坏,试件主控面特征明显,且主控破裂面劈裂角度在80°~90°;混凝土蠕变破坏失稳过程分为未破坏高应力水平下蠕变应变的持续增加与破坏高应力水平下蠕变应变的加速灾变,Burgers-Kelvin模型更符合高应力水平区混凝土试件的蠕变特性。Creep properties of concrete specimen in high-stress area are complex. Tests on uniaxial compressive strength and compression creep on two groups of twenty same concrete specimens in two loading rate are operated by RLW-2000 triaxial rheology servo test system. The relationship between the creep strain rate of concrete specimen and the stress level is studied. Creep and strength characteristics are analyzed in a high-stress area. The creep failure form and instability mechanism are determined. The concrete creep model is established in high stress and the relationship between creep test curve and the- oretical one is obtained. The results show that： The less stress levels on concrete specimen are in a high stress area, the greater creep failure strain rate is, the creep strain rate decreased integrally with creep failure stress increases. The total creep failure strain is more than the total instantaneous failure one in a high stress area and creep failure strength is 79.97%-88.85% of instantaneous one. The creep failure of concrete specimen shows mainly a compression-splitting damage in a high stress area, the ＂X＂ compression-shear failure occurred in partial specimen, the major master surface is obvious, and the major master surface angle is 80°-90°. Concrete creep failure instability includes the creep strain con- tinuous increasing in non-failure high-stress level and its cataclysm accelerate in failure high-stress lev- el. The Burgers-Kelvin model is appropriate for creep characteristics of concrete specimen in a high-stress area.

关 键 词：高应力水平 混凝土 蠕变特性 强度特征 失稳形态 

分 类 号：TU452[建筑科学—岩土工程]